Oscillation circuit



Jan. 1, 1929. 1,697,328

w. SCHEPPMANN OSCILLATION CIRCUIT Original Filed Aug. 51, 1921 Patented Jan. 1, 1929.

UMTE stats re -FFI-CE,

WILHELM SGHEPIPMANN, OF BERLIN-TEMPELHOF, GERMANY, ASSIGNOR '10 0, LORENZ AKTIENGESELLSCHAFT, 0F BEBLIN-TEMPELHOF, GERMANY.

OSCILLATION CIRCUIT.

Original application filed August 31, 1921, Serial No. 497,316, Patent No; 1,588,813, dated June 15, .1926, and in Germany November 29, 1917. Divided and. this, application filed May 13, 1926 s i N0 oasei.

(GRANTED UNDER THE PROVISIONS or THE nor 01: MARCH 3, 1921,41 STAT. L, 1313.

My invention relates broadly to oscillation circuits and more particularly to an electron tube circuit having an arrangement of parts for the generation of sustained oscillations.

This application the invention for which is disclosed and claimed in the German application L45,896, filed November 29, 1917 and which has matured into German Patent 216,814: issued July 27, 1925, is a division of my application Serial No. 497,- 316, filed August 31, 1921, for oscillation circuits which has matured into Patent 1,- 588,813;

It has become-known in the use of vacuum tubes with an auxiliary electrode as generators for the production of undamped electric oscillations, that the auxiliary electrode as wen as the anode must be coupled with an oscillation circuit in order on the one hand, to transmit to the oscillation circuit the energy produced by the tube and, on the other hand, to conduct again to the tube, part of the oscillating energy which exists "in the oscillation circuit to excite the tube for producing 'undamped oscillat-ions, in other words to use a so-called return coupling. Generally in time practice, the two selt-mductances :tor the connection of the auxiliary electrode and of the anode with the filament, are both inserted in one oscillation circuit. These methods sulier from the inconvenience that the energy which is returned to the tube'for the, purpose of control must not exceed limits it the best efficiency has to be ensured. These arrangements can, therefore, not be used for a great wave range and for difierent degrees of energy without an alteration of the return coupling of the tube with the oscillation circuit. This is particularlyundesirable, as the alteration has often to be made by relatively moving coupled coils whose position is determined by the condition that they couple themselves in a degree determined by their relative positions.

A further inconvenience is caused by the coupled coils as comparatively a large amount of metallic material is thus embodied into the field of self-inductance oi the oscillation circuit, so that an unneces- Sary damping of this oscillation circuit and unnecessary losses inthe same are caused which is noxious, especially when the tube is used for receiving purposes.

These inconveniences-are avoided, according to this invention, by an arrangementof the two self-inductances, of which oneis connected between the auxiliary electrode and the cathode, and the other between the anode and the cathode, or forms a part of this oscillation circuit. Consequently the two self-inductances without any mutual magnetic coupling are connected only through the intermediary of the anode and ot the auxiliary electrode (grid) in contra distinction to the arrangement mentioned above in which the two self-inductances are enclosed in one closed common circuit. The following result is obtained from the insertion of only one of the two selt-induetances 1n the primary oscillation circuit or from the coupling of this one self-inductance with said primary oscillation circuit.

In order to excite the tube for the productlon of oscillations it is necessary'that between cathode and anode or auiriliary electrode a periodic potential difference be produced in the rhythm in which the oscillations are maintained. The rhythm itself is determined by theelectric value of the circuits between the cathode and anode and between the cathode and grid. To produce the necessary potential a self-inductance is inserted between the cathode andone ofthe other electrodes, the energy produced being taken "from the cathode and from the electrode which is still free.

The arrangement can be used not only for the transmissionot energy but also as a receiver, in which case relay-action occurs in the well-known manner.

"Figures 1 and 2 of" the accompanying drawing show by way of eXampletwo con nections for theexecution of the method of my present invention.

In the connection shown by Fig.1, the cathode is and the anode a are coupled with the oscillation primary system (antenna), the cathode is and the anode a being connected with the antenna self-inductance 8 across the high tension battery it provided with a shunting condenser, The primary oscillation system is completed by the tuning condenser 0. A self-inductance is i1 serted between cathode and grid whereby the grid 9 obtains a potential difference with regard to Z6. 7

In this connection the self-inductance which is inserted in the primary circuit (antenna) forms, therefore, a part of the same.

According to F ig. 2 the connection can be arranged so that grid 9 and cathode 7c are coupled with the oscillating primary system. 8, c by a self-inductance 8,, whilst the anode is connected with the cathode by the coil 8 in series with the battery 72.

The value of the self-inductance 8 which does not form part of the oscillation system depends .within certain limits on the wave length but it is not critical. Under certain conditions the value of self-induction resulting from the connecting conduits between the electrodes will be sufiicient.

The current in the oscillating circuit is maintained thereby and the losses from radiation and damping are made up by a supplementary current generated in the tube circuits. It is necessary for the current to bear a proper phase relationship in the tube circuits, otherwise, instead of adding new energy to the circuit, energy is detracted. The existence of currents in the tube circuits is solely conditioned by the difference of po tential between grid 9 and the electrode 70 in the form of the filament, whereby the latter must have negative potential. If this is not the case, no current is possible. If, therefore, the difference of potential between grid 9 and 7c can be changed at the proper moment, so that the tube current furnishes only addition to the oscillation energy, a continuing oscillation will take place. For this purpose the coil 8 located between grid and the cathode, serves as a controlling means which operatesas follows:

The addition to the tube oscillating current is furnished only during a short portion of time of each half cycle as it takes a certain time for the self-inductance 8 to as sume its maximum current and to produce sufficient phase lag of the grid potential. Thus the oscillation maintaining potential is set up in the form of impulses during each half cycle which is in contra-distinction to the well known reaction 'inethod above referred to whereby a steady coupling between the oscillatory circuit and the con trol circuit is present. The present system has the advantage that a more effective control of the oscillations in the oscillatory circuit may be carried out whereby the efliciency of the oscillating system is increased.

l/Vhat I claim and desire to secure by Letters Patent of the United States is as follows:

1. In a system for the generation of rapid electrical. oscillations by means of a vacuum tube comprising an incandescent cathode, an anode and .a grid element, an output oscillatory circuit connected between said cathode and anode, adapted to produce initial. free oscillations, means for controlling and sustaining said oscillations in said output circuit consisting of substantially pure self-inductance connected between said cathode and grid without any further coupling connection with said first mentioned oscillatory circuitQ 2. In an arrangement for the generation of rapid electrical oscillations by means of a vacuum tube having an incandescent cathode, an anode and a grid element, an

output oscillatory circuit connected between I said cathode and anode-electrodes adapted to produce initial free electric oscillations,

an oscillation selfcontrolling and sustaining means consisting of a substantially pure self-inductance connected between said cathode and grid element andhaving no connection with said output circuit except across the grid and anode of the tube.

3. In a system for producing oscillation of carrier frequency, a vacuum tube, an output circuit and control circuit therefor said control circuit consisting of a substantially pure self inductance having no external connection with said output circuit.

4.. In a system for producing oscillations of carrier frequency, a three element tube comprising an output circuit and an input circuit, said input circuit consisting of a pure self-inductance being outside of said tube electrically disconnected from said output circuit and serving as control element of the oscillations in said output circuit.

5. In a system for producing oscillations of carrier frequency, a three element tube comprising an output circuit and an input circult, said input circuit being electrically disconnected from said output circuit outside of said tube and means consisting of substantially pure self inductance including said input circuit for controlling oscillations in said output circuit.

6. In a system for producing oscillations of carrier frequency, a three element tube, an output circuit therefor, an input circuit electrically disconnected from said output circuit outside of said tube whereby no coupling exist therebetween. and means consisting of substantially pure self inductance including said input circuit for maintaining oscillations in said output circuit.

7 In a system for producing oscillations, a three element tube, an output circuit therefor, an input circuit electrically disconnected from said output circuit outside of said tube whereby no coupling exist therebetween and means consisting of substantially pure self inductance including said input circuit for maintaining said oscillation in said output circuit, the electrical condition of said input circuit being electrically controlled by the electrical condition of said output circuit.

8. In an electrical circuit for producing oscillations, a three element tube, an input therefor comprising a substantially pure self inductance, an output circuit therefor comprising self inductance, said inductances being electrically and magnetically sepa rated to prevent coupling therebetween the electrical condition of said input inductance being controlled by the oscillations in said output inductance.

9. In an electrical circuit for producing oscillations, a three eleinent'tube, an input therefor comprising a substantially pure self inductance, an output therefor comprising a self inductance, said inductances being electrically isolated to prevent coupling therebetween, the electrical condition of said input inductance being controlled by the oscillations in said output inductance for maintaining said oscillations in said output inductance.

WILHELM SGHEPPMANN. 

